1. Field of the Invention
The present invention generally relates to a wireless charging apparatus and a portable terminal including the same.
2. Description of the Related Art
In general, portable electronic devices include portable terminals, MP3 players, portable multimedia players (PMPs), and electronic books, and refer to devices by which users can access various contents while carrying them. In particular, various functions have recently been integrated in portable terminals, specifically, smart phones. The portable terminals have a near field communication (NFC) function for payment or user verification through security cards for verifying incoming and outgoing people, traffic cards, credit cards, and the like. Such a portable terminal includes a separate antenna to perform the NFC function such as that described in Korean Patent Publication No. 2009-126323 (published on Dec. 8, 2009).
The portable terminal includes a detachable or embedded battery to supply electric power to the portable terminal. A user can charge the battery according to a battery level of the battery. Charging of batteries may be generally classified into wired charging and wireless charging. Wired charging is generally widely distributed, but various technologies for wireless charging are currently being developed. The wireless charging technologies include an inductive coupling type using magnetic fields, a capacitive coupling type using electric fields, and a radio frequency radiation method. The inductive coupling type is suitable for wireless charging in the aspect of power efficiency. In the inductive coupling type wireless charging, a primary coil provided in a charger and a secondary coil provided in a terminal are arranged such that the terminal can be charged. Such wireless charging technology is disclosed in Korean Patent Publication No. 2008-32519 (published on Apr. 15, 2008) and the like.
FIG. 1 is a view schematically illustrating a wireless charging apparatus mounted to a terminal for wireless charging according to the prior art. FIG. 2 is a view schematically illustrating the rear side of a shield member to which a secondary coil is mounted and a driving circuit unit according to the prior art. Referring to FIGS. 1 and 2, an NFC antenna element substantially in the form of a loop antenna and a secondary coil for wireless charging are mounted to one terminal to provide the terminal with the NFC function and the wireless charging function. The driving circuit unit connected to the NFC antenna element and the secondary coil for wireless charging is provided at one side of an upper end thereof. The shield member is used to interrupt the antenna element and the secondary coil from interfering with each other and to prevent an operation of the secondary coil from influencing the other circuit units in the terminal when the antenna element and the secondary coil are operated, respectively.
In the case of the wireless charging apparatus, heat is generated in the driving circuit unit during charging. FIG. 3 is a view obtained by measuring a temperature distribution of heat generated after wireless charging according to the prior art. Referring to FIG. 3, since the heat generated by the driving circuit unit cannot be dispersed to the outside, heat is concentrated only at a local portion such as a hotspot to be emitted. Since an antenna for communications of the portable terminal, a loop antenna, and an NFC antenna element are provided at a peripheral portion of the heated driving circuit unit, they are influenced by the generated heat, and since the generated heat cannot be dispersed, the performance of the driving circuit unit deteriorates due to the heat.
A material such as graphite may be applied to the driving circuit unit to disperse the emitted heat, but, as a result, the NFC antenna element may deteriorate or the wireless charging efficiency may be lowered, causing various problems such as a charging defect. Further, the wireless charging apparatus has many restrictions in realizing a heat dispersing structure at points other than the driving circuit unit due to mounting of the antennas.